Collaborative Research: The interplay between host diet, immunity, reproduction, and the microbiome across an anthropogenic-disturbed landscape

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It has recently become evident that microbes within the digestive tract of an animal are not only important for digestion but also influence overall health. An animal lives with trillions of microorganisms in its body, yet the implications of having most of these microorganisms are unknown. What is known thus far has focused primarily on the importance of microorganisms for digestion. However, current work suggests that an animal's microbes have effects that extend far beyond the gut, impacting the immune system and even stress. This project seeks to understand the importance of these microorganisms for health and survival in free-living populations of endangered iguanas that are exposed to changing and unnatural diets via ecotourism. The project will test how changing microbial communities and key physiological parameters relate to reproduction and survival in natural populations. Additionally, in the laboratory the researchers will experimentally test how changes in diet, stress, and microbes affect health and physiology in order to understand what is causing the observed changes in wild iguanas. Connecting physiological and microbial changes with animal population fluctuations in nature will be an innovative step forward. Finally, understanding both the occurrence and direction of these interactions will provide important insights into the effects of human-induced diet shifts on wildlife and much needed biological knowledge regarding threatened species. Humans have microbes in their digestive track as well, thus this project project may have broad implications on human health in relation to diet and stress. Many recent studies have identified significant connections between the microbiome and host health in model systems. However, mechanistic links between the microbiome and physiological functions that are key to health and survival remain mostly unexplored. Given that evolutionary history is one of the primary determinants of microbiome composition, the lack of taxonomic breadth severely restricts understanding of the physiological link between host habitat, diet, and immunity with microbiome composition and metagenomic function. There is also a paucity of research investigating microbial communities and health-related metrics within free-living animals. Thus, current knowledge of these relationships lacks critical ecological relevance and an understanding of the impact of environmental changes on endo-microbial communities. To address these current knowledge gaps, the project will study iguanas in both natural and captive settings, in order to test relationships among ecoimmune indices, anthropogenic-based diet changes, and the microbiome across a fragmented, insular landscape in The Bahamas. In the laboratory, the principal investigators will perform ecologically-relevant experimental manipulations in captive iguanas to test directional relationships in wild populations. The principal investigators will also investigate the stability of these associations over time in conjunction with a long-term mark recapture data set (37+ years) to estimate the influence of ecoimmunological, oxidative, and microbiome indices on reproductive output and survival across different populations exposed to variable human influence.This award was co-funded by the Division of Integrative Organismal Systems, the Division of Environmental Biology, and the Rules of Life Venture Fund within The Directorate for Biological Sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.